Powder cladding



April 2, 1963 F. E. LEIB ETAL POWDER CLADDING Filed June 8, 1959 United States Patent Of 3,083,407 POWDER CLADDING Francis E. Leib, Mount Lebanon Township, Allegheny County, Pa., and John F. Freeman, Worthington, Ohio, assignors, by direct and mesne assignments, to Copperweld Steel Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 8, 1959, Ser. No. 818,808 6 Claims. (Cl. 18--9) This invention relates to improvements in the cladding of a core rod or wire by the application of powder to the core surface. More particularly, this invention pertains to compacting of powder cladding material against a core surface in graduated thickness for the controllable elimination of air or gas that might otherwise be trapped in the cladding material.

In the production of clad rods and wires such, e.g., as the Alumoweld aluminum cladding of a ferrous core by the system described in United States patent application Serial No. 773,125, filed June 16, 1958, which application is owned by the assignee of the present application, we have discovered that it is desirable to inhibit entrapment of air which may occur on occasion in the course of the application of powder cladding material to the core surface during the continuous manufacture of such clad rods and wires. The powder material as purchaseable commercially is in a dry condition in sealed containers. In the course of the handling of the powder and the application thereof to a core rod or wire, air may sometimes be entrained or entrapped in the compacting stage of the manufacturing operation to an extent which upon heating in the heating stage may cause some local blistering, or a bursting in some cases, to the detriment of the quality at that particular locality of the end product.

This invention remedies the foregoing difficulty and inhibits such entrainment or entrapment by a transverse graduation of the thickness, reflecting pressure graduation, during roll compacting of the cladding powder against the core surface to achieve what appears to be a relatively very dense and a somewhat less dense area transversely, with enough porosity in the latter portion that air or gas may readily escape in the course of heating without localized blistering or bursting. Thereby, the quality of end product clad rods and wires free of local defect is enhanced and promoted.

Other objects, features and advantages of this invention will be apparent from the following description and accompanying drawings, which are illustrative of one embodiment only, in which:

FIGURE 1 is a view in side elevation of a portion of a powder applying compacting roll stand embodying this invention;

FIGURE 2 is an end view of a portion of the apparatus shown in FIGURE 1 to illustrate, schematically, a roll pass for practicing this invention in the illustrated embodiment;

FIGURE 3 is a cross section of a compacted and definned green clad rod taken along line IIIIII of FIG- URE 1, and

FIGURE 4 is a cross section of an end product clad rod following heating, hot reduction and finish operations on a green clad rod, as shown in FIGURE 3, of a nature described in the aforesaid United States patent application.

Referring to the drawings, which are not to scale, FIGURE 1 illustrates :a compacting rolling mill stand having a metal core rod or wire 11 moving along a work or pass line in the direction of arrow 12 through a powder applicator 13 where a concentric layer of cladding powder is applied thereto at the entry thereof into 3,083,407 Patented Apr. 2, 1963 a closed pass 14 formed by grooves 15 in respective Turks head rolls 16 when the rolls are screwed down to closed position. The exiting green clad rod portion with fins thereon enters a fin shaver 17 where the fins are removed and .then a roll guide 18 from which the definned compacted green clad rod portion 11b moves on to heating, reduction and finishing stages. The axis of the work rod portions 11, 11a and 11b is the axis of the pass line through the respective equipment items comprising the plant and at the conclusion of such stages, the composite clad rod or wire end product 19 having a ferrous core 20 and a continuous coherent cladding 21, the original powder particles of which are bonded to each other and the cladding of which is bonded to the core without, in the case of aluminum cladding on a ferrous core, any continuous layer or detrimental quantity of brittle aluminum-iron compound at the interface. The invention is applicable to powder cladding whether or not the core material is rod or wire or of other shape and of the same or dissimilar composition to the cladding material.

Pursuant to this invention, the powder cladding material is densified as core and cladding go through compacting pass 14 to produce a cladding layer of graduated thickness as shown by the contour of pass 1-4 and the shape of the green cladding on the illustrative clad rod shown in FIGURE 3. Thus, the radial thickness at crown point 22 of each are pressed by a particular groove 15 of the four mating Turks head rolls 1-6 is radially nearer to surface 23 of core 11 than are the portions 24 of the cladding segment produced by the sides near the edges of the respective groove 15, irrespective of whether or not the rolls are contoured with corner Vs 25 at the inner ends of mating parting surfaces 26, to produce triangular overfills integral with the fins. The remainder 27 of such overfills are shown in FIGURE 3 following defiuning by a shaver 17, one embodiment of which is more fully described in United States patent application Serial No. 818,715 filed June 8, 1959, for Shaver, which application is owned by the assignee of the present application.

In other words, by flattening the arcs of the grooves 15 defining pass 14, it is possible to graduate the compaction of cladding from a more dense condition intermediate the parting planes defined by each pair of mating parting surfaces 26 to a still compact but somewhat less dense condition adjacent those parting planes with suflicient porosity in the cladding areas 28 adjacent the base of each fin location in radial alignment with the overfill portions 27 as shown in dotted outline for one of such fins 274. It appears that as a consequence, during roll compacting by mill 1!) of the power cladding to produce the compacted green clad rod portions 11a and [1b, any air or other gas or vapor in the powder tends to migrate to areas 28 where porosity is suflicient for that air or gas or vapor to escape readily from the cladding. Hence, entrapment is inhibited along with blistering and bursting upon heating and hot working, with consequent benefit to the quality of end product, such as that illustratively shown for example, in FIGURE 4. In such heating and hot working treatment of a. definned compacted green clad rod, such as that shown in FIGURE 3, the respective areas 28 are densified and the cladding bonded for the production of the relatively uniform end product clad rod or wire.

Various changes may be made in details of the illustrated embodiment, and other embodiments provided, without departing from the spirit of this invention or the scope of the appended claims.

We claim:

1. In a metal powder cladding device to clad a metal or wire core moving along a pass line with metal powder material, apparatus comprising, in combination, a plurality of mating Turks head rolls the axes of which lie in a plane perpendicular to the axis of said pass line, each roll having a circumferential groove therein to provide a closed circular pass in the nip of said rolls, each of said grooves presenting a smooth continuous arc in cross section the edges of which are substantially equidistant from the respective axis of rotation thereof, the radius of curvature of the center of said are being slightly greater than the radius of curvature at the ends of said are to provide a substantially circular but slightly flattened arc, whereby powder cladding compacted by said rolls will be somewhat more dense in portions thereof opposite to the centers of the groove arcs in said rolls, respectively.

2. In powder cladding, the steps comprising, in combination, moving a rod or wire core along a pass line, concentrically feeding a substantially uniform layer of powder cladding material in the direction of movement of and into engagement with the surface of said core, compacting and densifying said layer so that the radial thickness thereof is graduated transversely around successive portions of said core to vary the density of said layer with sulficient porosity in a thicker area in said portions for escape of gas.

3. In a powder cladding device for compacting a substantially uniform layer of metal powder material as cladding against an elongated harder metal core, apparatus comprising, in combination, means for relatively moving said core axially through said device, means for feeding a layer of said material of substantially uniform thickness against said core, means for rolling said material into relatively dense compaction against said core substantially in the direction of said moving, said last-- named means having a continuous roll surface extending in the direction of movement of said core and symmetrical to each side of a plane normal to the axis of rotation of said roll surface and passing through the axis of said core, said roll surface being in graduated spatial relation to the surface of said core in a transverse direction to each side of said plane relative to the direction of said movement, said compaction approaching the density of solid metal in denser portions of said cladding material nearer said plane whereby powder cladding of said material compacted by said roll surface will be transversely graduated in thickness for readier movement of any gas toward and escape thereof from a relatively thicker portion of said compacted cladding material.

4. In a device for compacting relatively continuous particulate material, which is relatively nonextrudable at ambient temperature, as cladding against an elongated core member having a cladding surface beneath a layer of said particulate material in relatively uncompacted form, apparatus comprising, in combination, means for longitudinally moving said elongated core member and a substantial peripherally continuous layer of particulate material against said cladding surface through said device, a pressure member having a pressing surface for said layer of particulate material movable to a predetermined close distance from said cladding surface to cause said particulate material to be relatively densely compacted thereagainst by said pressing surface of said pressure member, means for so moving said pressing surface of said pressure member, said pressing surface in operative position being spaced nearer to said cladding surface at at least one place on said pressing surface and progressively farther from said cladding surface to the side of said one place transversely of the direction of said longitudinally moving of said elongated core member to compact said particulate material against said cladding surface with a density after compacting which will vary transversely and inversely relative to said progressively further spacing of said pressing surface for readier escape of gas from a portion of lesser density in said compacted particulate material cladding.

5. Rolling process to densely compact powder metal cladding, relatively non-extrudable at ambient temperature, against solid metal work, comprising, in combination, moving said work in a selected direction with a layer of said powder metal of appreciable predetermined thickness thereon, rolling in said direction said layer against said work with a selectively and transversely varied rolling pressure to compact said layer of powder metal against said work with correspondingly transversely varied densitication, said rolling pressure being varied progressively and transversely of said direction of rolling to force air or gas transversely from a portion of said cladding of greater compaction toward a portion of said cladding of lesser compaction, said portion of said cladding of lesser compaction having sufiicient porosity for readier escape of said air or gas.

6. In a metal powder cladding device to compact a layer of powder metal cladding against an elongated metal rod or wire core member moving axially along a pass line, apparatus comprising, in combination, a plurality of rolls each having a peripheral groove therein to provide a closed pass for said pass line in the nip of said rolls, each of said grooves presenting a transversely continuous concave surface corresponding generally to the shape of a transverse peripheral portion of said core member radially spaced from said concave surface toward the axis of said pass line, each of said peripheral grooves having a generally central element lying in a plane passing through the axis of said pass line, said central element being spaced a predetermined distance from the axis of said pass line, parallel elements in each groove to each side of said central element being spaced progressively farther from the axis of said pass line as the distance from said central element increases, and means for feeding powder metal positioned against said core member to said nip of said rolls for relatively dense compaction of said metal powder by said rolls against said core member with elements of said grooves farther from the axis of said pass line at said nip providing transversely spaced portions of said compacted powder metal cladding of corresponding lesser density and greater porosity, whereby, gas which may be in said cladding is forced toward and into said portions of lesser density and greater porosity for readier escape of such gas from said compacted powder metal cladding.

References Cited in the file of this patent UNITED STATES PATENTS 936,389 Wadsworth Oct. 12, 1909 1,510,745 Montgomery Oct. 7, 1924 1,544,305 Fisher Jan. 30, 1925 2,134,366 Hardy Oct. 25. 1938 2,184,971 Allen Dec. 26, 1939 2,386,604 Goetzel Oct. 9, 1945 2,603,114 Colinet July 15, 1952 2,620,513 Cryor et al. Dec. 9, 1952 2,760,229 Cheney et al. Aug. 28, 1956 

1. IN A METAL POWDER CLADDING DEVICE TO CLAD A METAL OR WIRE CORE MOVING ALONG A PASS LINE WITH METAL POWDER MATERIAL, APPARATUS COMPRISING, IN COMBINATION, A PLURALITY OF MATING TURK''S HEAD ROLLS THE AXES OF WHICH LIE IN A PLANE PERPENDICULAR TO THE AXIS OF SAID PASS LINE, EACH ROLL HAVING A CIRCUMFERENTIAL GROOVE THEREIN TO PROVIDE A CLOSED CIRCULAR PASS IN THE NIP OF SAID ROLLS, EACH OF SAID GROOVES PRESENTING A SMOOTH CONTINUOUS ARC IN CROSS SECTION THE EDGES OF WHICH ARE SUBSTANTIALLY EQUIDISTANT FROM THE RE- 